Design Of Lens System Research Articles

Quasi-null lens optical system for the fabrication of an oblate convex ellipsoidal mirror: application to the Wide Angle Camera of the Rosetta space mission

The design of a quasi-null lens system for the fabrication of an aspheric oblate convex ellipsoidal mirror is presented. The Performance and tolerance of the system have been analyzed. The system has been applied successfully for the fabrication of the primary mirror of the Wide Angle Camera (WAC), the imaging system onboard the Rosetta, the European Space Agency cornerstone mission dedicated to the exploration of a comet. The WAC is based on an off-axis two-mirror configuration, in which the primary mirror is an oblate convex ellipsoid with a significant conic constant.

A Design Tool for Aerodynamic Lens Systems

We report in this article the development of a tool to design and evaluate aerodynamic lens systems: the Aerodynamic Lens Calculator. This Calculator enables quick and convenient design of aerodynamic lens systems based on the parameterized knowledge gained from our detailed numerical simulations of flow and particle transport through aerodynamic lens systems. It designs the key dimensions of a lens system: pressure limiting orifice, relaxation chamber, focusing lenses, spacers and the accelerating nozzle. It also provides estimates of particle terminal axial velocities, particle beam width, and particle transmission efficiencies. This article describes in detail the information that is used in the design tool, including equations for pressure drop through orifices, contraction factors as a function of Reynolds, Mach and Stokes numbers, spacer length as a function of Reynolds number and estimations for the relaxation chamber dimensions. The article also evaluates the performance of the design tool by comp...

Microfabrication of massive parallel micromirror-lenses by X-ray LIGA technique: recent advances and prospects

Modern microfabrication techniques enable to obtain novel 2D lens systems which are the marriage of warped microchannel plates and Fresnel lenses. They rely on a multitude of precisely inclined micromirrors, acting together as very efficient macroscopic lenses for all electromagnetic wavelengths from the infrared, up to X-rays and even for particles like neutrons. Especially interesting is the fabrication of some-cm apertured lenses in the VUV and EUV region. X-ray LIGA is a favorite candidate for the fabrication of such lenses due to its inherent technological precision and capability to produce high aspect ratio structures. Theoretical consideration and limits for the design of such lens systems are presented, together with first investigations concerning surface-smoothing by spin-on glass in order to make such lens systems to work in the X-ray region.

Development and test of iron-free quadrupole lenses with high magnetic flux densities

Iron-free magnetic quadrupole lenses have been developed for the focusing of energetic bunched heavy-ion beams. These devices are operated in a pulsed mode and provide very strong magnetic fields. A magnetic flux density of more than 14 T has been reached in a 100 mm long quadrupole with a 20 mm wide aperture, which corresponds to a magnetic flux density of ∼1400 T/m. The pulse duration of the applied electric current is approximately 300 μs with a flat top of several μs. The calculated and measured field properties of the quadrupoles are presented. In a first test experiment with a fast-extracted 650 MeV/u 197Au 79+ beam (bunch length ∼500 ns) at GSI the focusing properties could be demonstrated. As a possible application the ion-optical design of a condenser lens system will be presented. With this system the phase-space enlargement in a nuclear reaction target can be significantly reduced, thus leading to an increased collection efficiency of a fragment separator or, more general, of any ion-optical device. In particular this is advantageous for injection of secondary beams into a storage ring.

Design and Evaluation of an Electron Objective Lens System with Two Lenses and Two Deflectors

The fundamental aberration coefficients of an objective lens system with two lenses and two deflectors for electron beam lithography system were investigated. First, we designed a two-deflector objective lens system by using computer simulations. The parameters of two deflectors (positions, strength, rotation angles) were optimized to compensate the transverse coma and transverse chromatic aberrations and the landing angle. The deflection aberration at the corner of the 2-mm field was almost the same as that at the center and was reduced by 35% compared with a one-deflector system. Next, all fundamental aberration coefficients, including the five geometrical aberration coefficients (spherical, transverse coma, astigmatism, field curvature, and deflection distortion), and two chromatic aberration coefficients (axial and transverse) were independently measured by using a practical objective lens system. The measured aberration coefficients agreed well with the simulated values. This agreement shows that the two deflectors successfully reduced the aberrations. It is concluded that this measurement is indispensable for designing and evaluating an electron objective lens system.

Design of Imaging Lens Systems that Use Low Dispersive Radial Gradient-Index Rod

Many effective lens design examples using gradient-index (GRIN) materials have been reported so far. However, the GRIN materials that were used in those designs are either very difficult or impossible to produce. We show an effective design and the design techniques of imaging lens systems that utilize realizable materials. The designed lens systems use flat-surfaced radial GRIN lens (Wood lens) with low dispersion, small Δn and small diameter.

Design and characterization of a high numerical aperture lens system for scanned laser lithography

Over the past decade, three generations of scan lens systems have been developed, culminating in a 33×, 364 nm, 0.8 numerical aperture lens system for 0.25 μm generation mask writing. The specifications and design performance of this latest lens from Tropel are compared with measurements made on a lens test bench and on a scanned laser writing system. A full-width at half-maximum spot size of 270 nm, and linearity performance under 20 nm have been measured. CD linearity data shows deviations less than 20 nm down to 0.3 μm feature sizes. Corner rounding data shows marked improvement over previous generation imaging optics with a minimum radius of 253 nm. These lens distortion and resolution measurements confirm that the new lens system has the imaging performance required for 0.25 μm generation masks.

A low-energy and low-emittance ion beam source for use with the super-microbeam production system (abstract)

We are developing a new type of microbeam system, intentionally utilizing the process of acceleration, accompanied with the beam contraction effect (conservation of normalized emittance). This device will enable one to produce microbeams for any ion species, less than 0.1 μm in diameter. A tentative design of lens system (ion energy=100 kV), composed of an entrance aperture lens and an einzel lens, will be described, and it will be discussed why the spherical aberration can be depressed much lower than the usual nonaccelerating lenses. The chromatic aberration due to the fluctuation of the acceleration voltage can be avoided in principle. Hence the only source of this type of aberration is the energy spread of the ion beam from the ion source. The maximum performance of this microbeam system may be obtained when the energy increasing ratio is large enough so that the incident beam energy is kept as low as possible. For investigating these points a hydrogen ion source of special design has been tested. It was found that the intrinsic energy spread can be made considerably low (∼0.5 eV) and a narrow parallel ion beam of several tens eV, which is nearly perfectly neutralized in space charge, can be obtained.

Design of gradient-index lens systems for laser beam reshaping

Refractive systems using two gradient-index lenses have been designed to convert a collimated Gaussian-profile laser beam into a plane wave with a uniform intensity distribution. The axial gradient-index distribution for two lenses is determined by using the energy conservation condition and the constant optical path-length condition. The design consideration and theoretical analysis are presented along with several applications.

Design of multielement acircular waveguide lens systems in anisotropic media

We discuss the evaluation and design of wide-field-angle acircular lens systems in anisotropic planar waveguides. After a short summary of the applied ray and wave optical relations, we examine the aberrations of systems that were optimized for an isotropic waveguide but are embedded in an anisotropic one. We show that effects of anisotropy must be taken into account in the design of wide-field-lens systems. We present a four-element acircular lens that was optimized using a merit function computed for uniaxially anisotropic media.

Design of zoom lens systems that use gradient-index materials

Some effective uses of the radial gradient-index (GRIN) lens in zoom lens systems are presented and lens design examples are shown. Also the effective Abbe number of a cemented GRIN lens is discussed and it is shown that a radial GRIN lens with uncommon dispersion can be replaced by a cemented radial GRIN lens with common dispersion.

Impact of quadratic phase factors on optical Fourier transforms and imaging

In the design of lens systems for coherent light processing, the occurrence of quadratic phase factors in the path of propagation is important for the determination of imaging and Fourier planes. The impact and propagation of quadratic phase factors can be described by simple fractional formulas similar to the well-known lens formula.

Engineering constraints and computer-aided optimization of electrostatic lens systems

Abstract An optimization tool for the design of electrostatic lens systems with axial symmetry is presented. This tool is based on the second-order electrode method combined with a multivariable numerical optimization procedure. The second-order electrode method makes a cubic spline approximation to the axial potential for a given electrode shape. With the help of this approximation, a numerical optimization can be done. To demonstrate this optimization tool, a lens system for Auger analyses is optimized. It is shown that variations in the practical constraints imposed on the design, like maximum electrode potential or maximum lens diameter, have strong effects on the obtainable lens quality. It is concluded that a numerical optimization does not take over the lens designer's job, but allows him to thoroughly examine the optical consequences of engineering choices by finding the optimum design for each set of constraints.

Performance Evaluation of a Novel Type of Low-Energy Electron Microscope

During the last few years the investigation of clean and adsorbate-covered solid surfaces as well as thin-film growth and molecular dynamics have given rise to a constant demand for high-resolution imaging microscopy with reflected and diffracted low energy electrons as well as photo-electrons. A recent successful implementation of a UHV low-energy electron microscope by Bauer and Telieps encouraged us to construct such a low energy electron microscope (LEEM) for high-resolution imaging incorporating several novel design features, which is described more detailed elsewhere.The constraint of high field strength at the surface required to keep the aberrations caused by the accelerating field small and high UV photon intensity to get an improved signal-to-noise ratio for photoemission led to the design of a tetrode emission lens system capable of also focusing the UV light at the surface through an integrated Schwarzschild-type objective. Fig. 1 shows an axial section of the emission lens in the LEEM with sample (28) and part of the sample holder (29). The integrated mirror objective (50a, 50b) is used for visual in situ microscopic observation of the sample as well as for UV illumination. The electron optical components and the sample with accelerating field followed by an einzel lens form a tetrode system. In order to keep the field strength high, the sample is separated from the first element of the einzel lens by only 1.6 mm. With a numerical aperture of 0.5 for the Schwarzschild objective the orifice in the first element of the einzel lens has to be about 3.0 mm in diameter. Considering the much smaller distance to the sample one can expect intense distortions of the accelerating field in front of the sample. Because the achievable lateral resolution depends mainly on the quality of the first imaging step, careful investigation of the aberrations caused by the emission lens system had to be done in order to avoid sacrificing high lateral resolution for larger numerical aperture.

Optimization of a thin-film multilayer design by use of the generalized simulated-annealing method

The generalized simulated-annealing method is a statistical optimization method for finding the global minimum of a multivariable function. It was initially used in complicated lens system design. We report success in applying this method to thin-film multilayer design. The local minima trapping problem mentioned previously [W. J. Wild and H. Buhay, Opt. Lett. 11, 745 (1986)] with the simulated-annealing method is not found here because of the use of a proper evaluation function [I. O. Bohachevsky, M. E. Johnson, and M. L. Stein, Technometrics 28, 209 (1986)]. The effects of the initial configuration and the random step size on the simulation process are discussed systematically.

Conceptual study of a toroidal electrostatic analyzer suitable for time-resolved XPS experiments with high flux synchrotron radiation sources

The use of new-generation synchrotron radiation sources for core-level photoemission will allow time-resolved experiments. On the other hand, the high flux will give rise to detector saturation problems. We present an electron analyzer which, because of its unique focusing properties, completely solves the difficulty. Moreover, because of its rotational symmetry, it will allow a simpler and more efficient design of the input lens system.

Some remarks on computer-aided design of optical lens systems

Computer-aided design of optical lens systems implies the solution of an optimization problem of large dimension. To apply a local algorithm, we want to know a starting point within a small neighborhood of the desired system. For a given task, the designer is not able to define a suitable starting point. In this paper, we describe a global optimization algorithm which uses the principles of biological evolution with the aim of locating an adequate starting point for a local correction routine.

Design of the individual components of a multicomponent lens system: use of a singlet

It has been recently shown that the complex problem of thin lens structural design of a multicomponent lens system with a prespecified set of primary aberration residuals and Gaussian characteristics can be reduced to the problem of design of individual components with specified Gaussian parameters and central aberration targets. This paper reports a systematic approach to study the feasibility of using singlets for the individual components. The method provides an analytical procedure to select the optimum glass in a semiautomatic manner. It also attempts to ascertain the practical viability of a singlet solution by considering the possible effects of the structure of the singlet on higher-order aberrations. A set of graphs for rapid study of the feasibility of a singlet solution is also presented.

Design of gradient-index lens systems for disc format cameras

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text J. Brian Caldwell and Duncan T. Moore, "Design of gradient-index lens systems for disc format cameras," Appl. Opt. 25, 3351-3355 (1986) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Model for the chromatic properties of gradient-index glass

A model has been developed which predicts the chromatic properties of gradient-index materials based on the composition of the glass. It yields a gradient Abbe number and a gradient partial dispersion which can be used by the lens designer in the design of achromatic gradient-index lens systems. Over 100 glasses with various ion exchange pairs have been investigated. The result is a gradient Abbe number ranging from −2000 to +5000 and a gradient partial dispersion ranging from −5 to +7. This wide range of gradient Abbe numbers and gradient partial dispersions can be further extended by using a glass which has two exchange ions with one diffusing ion or a glass which has one exchange ion with two diffusing ions. In addition to an extended range, the designer is afforded the luxury of a continuously varying Abbe number rather than the discrete Abbe number of conventional materials.